Manufacture of leather



Patented Sept. 13, 1938 MANUFACTURE OF LEATHER Gustav Mauthe and HermannNoerr, Leverkusen- I. G. Werk, Germany, assignors to I. G.Farbenindustrie Aktiengesellschaft, Frankfort-:01:- the-Main, Germany NoDrawing. Application November 21, 1935, Se-

rial No. 50,989. In Germany November 28,

9 Claims. (Cl. 1495) agents display some properties which impair nucleiin asimilar manner, the effect is dependent their value. For example,after the usual rinson the constitution. The simple sulphonic acids ing,greasing and drying, they exhibit a rather of benzene and naphthaleneshow a relatively hard feel. Although this is somewhat improved small,although noticeable e c W ch esults by subsequent staking, even then thefinished in a somewhat softer feel and an improvement in 10 leatherstill leaves much to be desired in this rethe fullness of the leather. Aconsiderable inm spect. A further disadvantage consists in the crease ofthe efficacy is attained y r pl cin the fact that the color of thefinished zirconiumsimple sulphonic acids by, for example, substitannedleathers has a somewhat yellowish shade tuted triphenylmethane sulphonicacids, such for which can be noticed even if pure zirconium cominstanceas tetrachloro-dihydroxyp y pounds have been employed and if theleathers methane sulphonic acids. 15 have been greased withlight-coloured water- The treatment may be preformed in various solubleoils. ways and at various stages of the tannage. It

In accordance with our invention, these diss po s for instance. to p oyt e said comadvantages can be diminished or practically Pounds in thePlace Of the usual neutralizing completely overcome. agents such assodium bicarbonate; they may 20 The process of this invention comprisesthe step o be a d to the tanning liquor q ent ofacting on the leathers,during or after tanto neutralization. A further possibility consistsnage, with non-tanning water soluble sulphonic in the after-treatment ofthe tanned leathers in a or carboxylic acids containing aromatic nucleior f es b t before after the usual rinsing water-solublesalts of suchsulphonic or carboxpr Even small amounts f the aromatic 25 ylic acids Bythe term non-tanning, as used comp s e fi c t, and they may be cmaboveand in the appended claims, such comployed as such or in admixture withone another; pounds are meant which, when used alone, are on an averagethere is employed about 0.5 to 5% not capable of converting the animalskin into ca d on the We t o e hides.

3o leather. According to a further feature of our In a c s the treatmentresults in n 80 invention the said improvement becomes still provedtakin p f fat n n mpr vement in more obvious if such aromatic compoundsare the qu y of the leather s regards color, softused the molecularWeight of which has been ness, fullness or feel. increased either bylinkage of several nuclei or The following p s ate t e invention 5 bysubstitution, for instance, by hydroxyl groups without limiting itthereto, the indications in or chlorine. per cent being calculated onthe Weight of the For instance, whereas the effect with benzoic hides:-Example 1 acid is still rather small, the use even of dichlorobenzoicacid results in an evident improvement in Pickled Calf hides are treatedWith an aqueous 4n the leather quality as regards fullness and color. ono sodium chloride and co ium sul- A similar good result is obtained bysubstituting ohate until y are l struck hrou h. The into the molecule anaromatic nucleus, for inleather thus prepared is treated for One to twostance a benzoyl residue. A considerable 1 hours in the drum with 100%of water and 5% provement can be attained by the application of Of thesodium salt Of naphthalene -d u compounds containing hydroxyl groups has phonic acid. The leather is then well rinsed, 5 chlorohydroxybenzoicacid. The aromatic digreased, dried, Stretched and e A White carboxylicacids display a similar behaviour. leather of improved ss and outstandinWhereas, for example, the efiect obtained by usfastness to i t isObtaineding phthalic acid is not yet sufficient for all prac- Example 2tical purposes, dichloroor tetrachlorophthalic 5 acids prove themselvesto be excellent auxiliary Pickled calf hides are treated in accordanceagents, as besides effecting an improvement in with the directions givenin Example 1, the socolor, softness, grain and resisting capacity todiumsalt of naphthalene 1.5-disulphonic acid wards hot water, they yieldleathers which are being replaced by the same amount of the sodium 5absolutely fast to light. Here too the more comsalt of2.2-dihydroxy-3.5.3.5'-tetrachloro-tri- This invention relates toimprovements in the manufacture of leather.

, Minerally tanned leathers prepared with the aid of water solublezirconium salts as tanning plicated compounds, for example thosepossessing two nuclei in the molecule, such as terephthalylbenzoic acid,display an outstanding efiect.

With the sulphonic acids containing aromatic phenylmethane 2" sulphonicacid. By this treatment the softness and the whiteness of the leatherare still more improved than by the treatment in accordance with themanner described in Example 1.

Example 3 Example 4 A treatment is performed in accordance with thedirections given in Example 3, replacing the dichlorophthalic acid byterephthalyl-2-benzoic acid. Fullness, softness, feel and the resistingcapacity towards hot water are considerably improved in comparison withnon-after-treated zirconium sulphate-tanned leathers; the fastness tolight is scarcely less than that of the product prepared in the mannerdescribed in Example 3.

Example 5 A calf hide tanned with zirconium sulphate is after-treatedwith 5% of the sodium salt of 2.5- dichlorobenzoic acid in 100% ofwater, whereby, after rinsing, greasing and drying, an improvement inthe fullness and softness of the leather is obtained.

' Example 6 Instead of the sodium salt of dichlorobenzoic acid mentionedin Example 5 the sodium salt of 4-chlorobenzoyl-2-benzoic acid can beemployed with the same success.

Example 7 The dichlorobenzoic acid salt of Example 5 is replaced by thesame amount of 5-chloro-2-hydroxybenzoic acid. Besides improvedfullness, a finer white and a greater resisting capacity towards hotwater is attained.

Example 8 A piece of goat hide which has been tanned with 8% of sodiumsulphate and 2.5% of zirconium dioxide (as ZrOC12.8H2O) in 100% of wateris after-treated.for two hours in a fresh bath to which 2% of a mixtureof the sodium salts of the dichloro and tetrachloro-phthalic acids areadded. The hide is then thoroughly rinsed, greased with a light-colouredwater-soluble oil and pole-dried. Whereas a hide which has not beentreated in accordance with the process of this example and which hasonly been rinsed, greased and dried, shrinks very much and is hard afterdrying, the after-treated leather is much softer and fuller andpossesses an excellent fastness to light.

Eaample 9 A goat hide tanned with zirconium oxychloride anon-after-treated leather to those pointed out in Example 8.

We claim: a

1. In the process of tanning with zirconium salts, the modificationwhich comprises applying to the leather, during or after tannage, asolution having incorporated therein a non-tanning compound containingan aromatic nucleus selected from the group consisting of watersolublecarboxylic and sulphonic acids and watersoluble salts of carboxylic andsulphonic acids.

2. In the process of tanning with zirconium salts, the modificationwhich comprises applying to the leather, during or after tannage, asolution having incorporated therein a non-tanning compound according toclaim 1, in which compound the aromatic nucleus contains a substituentgroup.

3. In the process of tanning with zirconium salts, the modificationwhich comprises applying to the leather, during or after tannage, asolution having incorporated therein a non-tanning compound according toclaim 1, which compound contains more than one aromatic nucleus- 4. Inthe process of tanning with zirconium salts, the modification whichcomprises applying to the leather, during or after tannage, a solutionhaving incorporated therein a non-tanning compound according to claim 1,which compound contains more than one aromatic nucleus and in whichcompound the aromatic nucleus contains a substituent group. I 5. In theprocess of tanning with zirconium salts, the modification whichcomprises applying to the leather, during or after tannage, a solutionhaving incorporated therein a non-tanning watersoluble halogenatedaromatic acid, which may be present in the form of a watersoluble salt.

6. In the process of tanning with zirconium salts, the modificationwhich comprises applying to the leather, during or after tannage, a solution having incorporated therein a non-tanning watersoluble halogenatedaromatic carboxylic acid, which may be present in the form of awatersoluble salt.

7. In the process of tanning with zirconium salts, the modificationwhich comprises applying to the leather, during or after tannage, asolution having incorporated therein a watersoluble salt of achlorophthalic acid.

8. In the process of tanning with zirconium salts, the modificationwhich comprises applying to the leather, during or after tannage, asolution having incorporated therein a watersoluble salt oftetrachlorophthalic acid.

9. In the process of tanning with zirconium salts, the modificationwhich comprises applying to the leather, during or after tannage, asolution having incorporated therein a mixture containing alkali saltsof di-, triand tetrachlorophthalic acids.

GUSTAV MAUTHE. HERMANN NOERR.

